The present invention relates to electrical power regulation and more particularly to centralized automatic control of regulators in a power distribution system.
In a typical power system, a distribution substation receives electrical power at a relatively high voltage such as 66kv and separately transforms the power onto individual three-phase distribution lines at a medium voltage such as 4kv. The distribution lines each extend from the substation to a plurality of consumer locations at which local transformers provide service at 120 volts or a multiple thereof. The distribution lines are each equipped with regulator transformers at the substation for controlling the distribution voltage as a function of input voltage and load current in order to maintain the service voltage at the consumer locations within a desired range. The three-phase distribution lines are typically regulated by three separate single-phase regulators, or by a single three-phase regulator.
Recent conservation measures, such as the Conservation Yoltage Regulation (CVR) program have imposed tighter operating constraints on distribution circuits. With the current guidelines for CVR, the first customer must average 120 volts or less while the last customer operates at 114 volts or above.
Many existing substation regulators of the prior art allow for excessive voltage variations, making it difficult to comply with the CVR program requirements. Additionally, these controls are not sufficiently responsive to the variety of load conditions that are experienced throughout the year. Thus more sophisticated regulation is required for providing better voltage control on the distribution circuit. However, the cost of replacing the regulators with ones having greater sophistication is prohibitive.
Thus there is a need for improved voltage control of power distribution lines that complies with the CVR program, that is responsive to both short and long-term loading conditions, is easy to operate, inexpensive to produce, and can be used with the existing regulators.